PHYS 183 Lecture Notes - Lecture 4: Celestial Equator, Right Ascension, Ecliptic
21 Apr 2018
School
Department
Course
Professor
Document Summary
Any position on the earth can be specified using longitude and latitude. Longitude specifies east/west position: montreal: lat= 45. 5 n, long = 73. 5 w. Meridian: the circle through the zenith connecting the north and south poles. The (cid:272)elestial e(cid:395)uato(cid:396) is the p(cid:396)oje(cid:272)tio(cid:374) of the ea(cid:396)th"s e(cid:395)uato(cid:396) o(cid:374)to the (cid:272)elestial sphe(cid:396)e. Every object in universe projected onto celestial sphere. Can project north pole onto sphere and is now north celestial pole (same with south) Every star has some position on the celestial sphere. Any point on the sky can also be specified with latitude and longitude. If dec = latitude, source passes directly overhead when ra crosses local meridian: declination (dec): analogy of latitude, right ascension (ra): analogy of longitude. Ra overhead is constantly changing as earth rotates. Astroptip: find your latitude using the north star, also known as polaris. Ma(cid:396)ks the app(cid:396)o(cid:454)i(cid:373)ate lo(cid:272)atio(cid:374) of no(cid:396)th (cid:272)elestial pole, (cid:374)o(cid:396)th e(cid:374)d of ea(cid:396)th"s (cid:396)otatio(cid:374) a(cid:454)is.
